1. Field of the Invention
The present invention relates to a technology for receiving moving-image data, which is an encoded moving image, from a part of a plurality of encoders that encodes captured moving images and distributing the received moving-image data to a client terminal.
2. Description of the Related Art
In a conventional moving-image distributing system, a moving-image server receives image data of MPEG4 (Moving Picture Expert Group 4) sent from an encoder, and distributes the received image data to a predetermined client terminal in a streaming form.
In this moving-image distributing system, degeneration is executed when a moving-image server has a failure. In the degeneration, a plurality of normal moving-image servers other than a failed moving-image server where a failure has occurred operates for the failed moving-image server.
A management server that manages individual moving-image servers presets presence/absence of storage setting, priority levels, and encoder IDs to individual encoders. There are three priority levels of high, medium, and low.
The management server allocates the priority according to the presence/absence of storage setting, and the ascending order of the priority levels, and IDs of encoders of which the failed moving-image server has been in charge, and assigns encoders to normal moving-image servers in the priority from a higher one. The management server forcibly stops operations of an encoder that cannot be handled by a normal moving-image server.
In a distributed processing system disclosed in Japanese Patent Application Laid-open No. H6-214962, a management node that manages a network prepares a plurality of combinations of operations and processing nodes which process the operations beforehand. When a failure occurs in a predetermined processing node, the management node selects a predetermined combination to back up operations of the failed processing node, and sends the selected combination to individual processing nodes, which back up the operations of the failed processing node based on the received combination.
However, because the priority is fixed, the conventional moving-image distributing system has a problem that the priority of the encoders cannot be changed dynamically.
For example, when a disaster or the like occurs at a location, and a fire department or the like wishes to know the situation of the disaster, an encoder that is closest to the location where the disaster has occurred and receives images of the disaster becomes important, however, the priority previously set to the encoder can be low.
That is, when an abnormality occurs in a moving-image server in charge of an encoder closest to the location where a disaster or the like has occurred, the operations of the encoder may not be assigned to a normal moving-image server and the operations may be forcibly stopped due to the low priority of the encoder.
Even when the management node allows a normal processing node to back up the operation of a failed processing node as disclosed in Japanese Patent Application Laid-open No. H6-214962, a combination of processing nodes and operations prepared beforehand is used, so that it is not possible to handle situations surrounding operations that always change.
It is therefore a very important issue to dynamically change the priority of each encoder according to the situations surrounding the encoder that changes sequentially.